Immunization of individuals has long been a known technique for controlling diseases such as measles, mumps, rubella, polio, hepatitis and, more recently, chicken pox. Conventional immunizations deliver either an attenuated live strain of a pathogen or a killed organism or an immunogenic antigen derived from the targeted pathogen or its products, or one produced using recombinant genetic technology. Classical immunization delivers the vaccine by injection or by the enteric route. This approach is very indirect, requiring the antigen to be taken up by immunocytes before or after dispersion from the injection site to the surrounding tissue. The immunocytes then migrate to lymphatic nodes or spleen where antigen processing continues, or, for live vaccines, where the attenuated vaccine strain organisms multiply and are disseminated from. Exposure of immunocytes to the antigens or the attenuated pathogens triggers humoral and cellular mediated immune responses, which lead to absorption of antigens or elimination of attenuants followed by long lasting protection from disease caused by the respective pathogen(s).
The enteric route requires that the antigen or organism survive the numerous barriers posed by the gastric acid, digestive enzymes, competing microorganisms and biologically active lumenal or tissue substances, to reach a site from which the antigen or attenuated organism or products derived from an organism can be absorbed and can stimulate the immune system inducing a protective response. Other approaches, such as anti-idiotype immunization, or DNA injection, have been proposed but have not yet proven efficacious or safe in humans.
The routes of immunization for conventional vaccines have been parenteral (intramuscular, subcutaneous or intradermal) or oral/enteric. Evidence exists that other routes (rectal, aerosol/nasal, dermal, etc.) could be used, but various practical and safety limitations have blocked widespread applications via these routes. Direct administration of vaccines via the intravenous route has been avoided due to the possible risk of severe systemic allergies (anaphylaxis) in sensitive individuals, or the risk of embolization of vaccine components or of air.
In any case, all routes to date are modeled on the existing concept of multiple vaccinations, using individual (monovalent) or combination (polyvalent) vaccines. A reduction in the total doses needed for parenteral vaccines has been limited by the lack of lasting immune responses after only one dose of some vaccines, by interference between antigens when combined, and sometimes by safety or stability issues.
The expense of and barriers to vaccination are aggravated not only by the growing number of vaccines, doses, clinic visits for vaccinations, etc., but the need to manufacture multiple formulations free from adventitious organisms, noxious ingredients and/or contaminants or impurities. Additionally, the necessity of cold chain maintenance for many vaccines raises another barrier against vaccination in remote and impoverished areas. Also, relatively large volumes and large doses of most current vaccines are needed to ensure that some of the vaccine is injected into areas where it will come into contact with immunocytes within tissue, and to generate responses of protective magnitude.
Due to the increasing number of vaccines being introduced for disease control, an additional series of problems have arisen with the use of conventional vaccines. These problems include:                (a) Excessive expense for the vaccine products, vaccine administration, storage and clinic/office visits.        (b) Problems of compliance with costly and complex vaccination schedules.        (c) Unavailability of certain vaccines in impoverished areas.        (d) Growing dependence on health care workers for delivery of the vaccines.        (e) Lack of health care workers in many areas.        (f) Multiplicity of injections with complex schedules and injection site discomfort.        
(g) Interference between certain antigens in polyvalent vaccines.                (h) Age restrictions for some vaccines.        (i) Production and supply limitations with frequent shortages.        (j) Safety concerns.        
In view of the multiplicity of concerns associated with the administration of conventional vaccines, there is a need in the art for a new and revolutionary method of immunizing individuals, both humans and animals, which mitigates the problems enumerated above.